AMMONIUM CARBONATE. 101 



with alternate layers of newly slaked lime and ammonium sulphate, 

 and spray afterwards with water, or with lime alone, and then spray 

 with a solution of sulphate of ammonia. The holes are then plugged 

 with clay or wooden plugs. The ammonia gas generated by the 

 mixture of these substances reaches the phylloxera, and infallibly 

 kills it. 



Mouillefert determined that if the phylloxera be sensitive to 

 ammonia it is difficult on the large scale to destroy it \vith ammonia- 

 cal liquor. A phylloxera-infested root dipped for three minutes in 

 ordinary ammonia, or exposed for an hour to the vapours of 5 cubic 

 centimetres of this substance in a 2-litre bottle was freed from all its 

 parasites, but these experiments repeated on a phylloxera-infested 

 vine in pot gave no good results. For that purpose 10 cubic centi- 

 metres of ammonia were poured into two holes which were immediately 

 plugged. The beards of the root in existence before the experiment 

 were destroyed and the swellings on the large roots still bore numerous 

 parasites. Ammoniacal liquor, according to this experiment, is not, 

 therefore, capable of destroying the phylloxera without imparting 

 grave injuries to the plant. In fact, 20 cubic centimetres of this 

 liquor employed in the same conditions ou a healthy vine burnt the 

 leaves, and 40 centimetres killed them. Ammonia used as vapour 

 does not appear to have the injurious action of ammoniacal liquor on 

 plants. Ammonium sulphate used according to Eosler's indications, 

 may thus have as great an action on the phylloxeras as it has on the 

 vine, by imparting new vigour to it in virtue of its nutritive properties. 



22. Ammonium Carbonate (NHJ0CO3.— Preparation. — By 

 heating in a cast-iron retort an intimate mixture of equal weights of 

 ammonium sulphate and chalk. The volatile salt is condensed in a 

 receiver. 



Properties. — Ammonium carbonate is a transparent crystalline 

 salt with a caustic taste and exhaling ammoniacal odour. In contact 

 with air it loses a part of its ammonia and is converted into a more 

 stable bi-carbonate. Solutions of ammonium carbonate are com- 

 pletely dissociated into ammonia and carbonic acid when heated. 



Use. — Hitchcock and Carleton have observed that a 1 per cent solu- 

 tion of ammonium carbonate stopped the growth of the uredospores of 

 Puccinia coronata, Corda, after seventeen hours' action. 



Phylloxera castatrix, Planch, (phylloxera of the vine), — The effects 

 of ammoniacal manure, such as ammonium carbonate, which stable 

 manure contains in notable quantities, have always been successful 

 on phylloxera-infested vines. Eosler ascribes this to the ready dis- 

 sociation of this salt into ammonia — especially poisonous to the 

 phylloxera — and carbonic acid. So as to render it still more active, he 

 advises the manure containing the ammonium carbonate to be spread 

 in the spring, because the young generations of phylloxera are much 

 more sensitive than the adults. Mouillefert is of another opinion. 

 According to his experiments a solution at the rate of 2 lb. of this 

 salt in 25 gallons of water with which he watered a phylloxera- infested 

 vine was incapable of killing the phylloxeras. He concluded that 

 ammoniacal salts only acted as fortifiers of the plant. 



